There are known hollow cylindrical filter elements that are used in liquid filters, e.g., to filter oil, and that comprise a filter medium body through which there is to be a radially inward flow from the outside. In the cylindrical interior space, there is a support frame that imparts stability to the filter medium body, which is composed of a non-woven material or a paper material. End caps are located at the end faces of the filter medium body, and the cylindrical interior space constitutes the clean side from which the purified fluid is axially discharged. For example, patent document EP 1 702 663 A1 describes such a filter element.
The filter element is used in a filter housing, and the filter element and filter housing together form a filter device. The filter housing is provided with ports for the supply of the crude fluid and the discharge of the pure fluid. For the purpose of fastening, the filter element may be inserted into a pot-shaped cover that can be placed on the housing and is intended to be connected thereto via suitable fastening devices. For example, the cover may be bolted to the filter housing.